Introduction

<boost/python/operators.hpp> provides types and
functions for automatically generating Python special methods
from the corresponding C++ constructs. Most of these constructs are
operator expressions, hence the name. To use the facility, substitute the
self object for an object of the
class type being wrapped in the expression to be exposed, and pass the
result to class_<>::def(). Much of
what is exposed in this header should be considered part of the
implementation, so is not documented in detail here.

Classes

Class self_ns::self_t

self_ns::self_t is the actual type of the self object. The library isolates
self_t in its own namespace, self_ns, in order
to prevent the generalized operator templates which operate on it from
being found by argument-dependent lookup in other contexts. This should
be considered an implementation detail, since users should never have to
mention self_t directly.

The tables below describe the methods generated when the results of the
expressions described are passed as arguments to class_<>::def().
x is an object of the class type being wrapped.

Class self_t inplace
operators

In the table below, If r is an object of type
other<T>,
y is an object of type T; otherwise,
y is an object of the same type as
r.

C++ Expression

Python Method Name

C++ Implementation

self += r

__iadd__

x += y

self -= r

__isub__

x -= y

self *= r

__imul__

x *= y

self /= r

__idiv__

x /= y

self %= r

__imod__

x %= y

self >>= r

__irshift__

x >>= y

self <<= r

__ilshift__

x <<= y

self &= r

__iand__

x &= y

self ^= r

__ixor__

x ^= y

self |= r

__ior__

x |= y

Class self_t
comparison functions

In the tables below, if r is of type self_t, y is an object of
the same type as x;
if l or r is an object of type
other<T>,
y is an object of type T;
otherwise, y is an object of the same type as
l or r.l is never of type self_t.

The column of Python Expressions illustrates the expressions
that will be supported in Python for objects convertible to the types of
x and y. The secondary operation arises due to
Python's reflection
rules for rich comparison operators, and are only used when the
corresponding operation is not defined as a method of the y
object.

C++ Expression

Python Method Name

C++ Implementation

Python Expressions
(primary, secondary)

self == r

__eq__

x == y

x == y, y == x

l == self

__eq__

y == x

y == x, x == y

self != r

__ne__

x != y

x != y, y != x

l != self

__ne__

y != x

y != x, x != y

self < r

__lt__

x < y

x < y, y > x

l < self

__gt__

y < x

y > x, x < y

self > r

__gt__

x > y

x > y, y < x

l > self

__lt__

y > x

y < x, x > y

self <= r

__le__

x <= y

x <= y, y >= x

l <= self

__ge__

y <= x

y >= x, x <= y

self >= r

__ge__

x >= y

x >= y, y <= x

l >= self

__le__

y >= x

y <= x, x >= y

Class self_t non-member
operations

The operations whose names begin with "__r" below will only
be called if the left-hand operand does not already support the given
operation, as described here.

Class Template other

Instances of other<T> can be used in operator
expressions with self; the result is equivalent
to the same expression with a T object in place of
other<T>. Use other<T> to prevent
construction of a T object in case it is heavyweight, when
no constructor is available, or simply for clarity.

Class Template other synopsis

Class Template
detail::operator_

Instantiations of detail::operator_<> are used as
the return type of operator expressions involving self. This should be considered an implementation
detail and is only documented here as a way of showing how the result of
self-expressions match calls to class_<>::def().